Hazardous Location Ratings Overview

Introduction

Hazardous locations are defined by the National Electrical Code (NEC) as areas "where fire or explosion hazards may exist due to flammable gases or vapors, flammable liquids, combustible dust, or ignitable fibers or flyings."

Underwriters Laboratories Inc. (UL) tests and certifies equipment for hazardous locations based upon their ability to protect users from specific environmental hazards. Hazardous locations are classified depending on their type, condition, and nature.

UL offers a full technical summary for hazardous locations:

• UL Hazardous Location Summary

The following HIS products have been tested and certified for hazardous locations:

Model No.	Description	Hazardous Location Rating
HIS-ML17-xxHx	17" Panel Mount LCD Monitor	Class I, II, & III, Division 2, Groups A, B, C, D, F, G; Temp Code T6
HIS-ML19-xxHx	19" Panel Mount LCD Monitor	Class I, II, & III, Division 2, Groups A, B, C, D, F, G; Temp Code T6
HIS-UM17-xxHx	17" Universal Mount LCD Monitor	Class I, II, & III, Division 2, Groups A, B, C, D, F, G; Temp Code T5
HIS-UM19-xxHx	19" Universal Mount LCD Monitor	Class I, II, & III, Division 2, Groups A, B, C, D, F, G; Temp Code T5
HIS-RL17-xxHx	17" Rack Mount LCD Monitor	Class I, Division 2, Groups A, B, C, D; Temp Code T6
HIS-RL19-xxHx	19" Rack Mount LCD Monitor	Class I, Division 2, Groups A, B, C, D; Temp Code T6

HIS-ML17, HIS-ML19, HIS-RL17, and HIS-RL19 are all certified under UL File No. E328481.

• Hazardous Locations Certification
• Hazardous Locations Certification for Canada

HIS-UM17 and HIS-UM19 are all certified under UL File No. E334953.

• Hazardous Locations Certification
• Hazardous Locations Certification for Canada

Hazardous Location Types

• Class I - locations where flammable gases or vapors may be present in the air in sufficient quantities to be explosive or ignitable.

• Class II - locations made hazardous by the presence of combustible dust.

• Class III - locations where there are easily-ignitable fibers or flyings present, due to the types of materials being handled, stored, or processed.

Hazardous Location Conditions

• Division 1 (Normal Condition) - the hazard would be expected to be present in everyday production operations or during frequent repair and maintenance activity.

• Division 2 (Abnormal Condition) - the hazardous material is expected to be confined within closed containers or closed systems and will be present only through accidental rupture, breakage or unusual faulty operation.

Nature of Hazardous Substances

• Class I Groups - Groups A (acetylene), B (hydrogen), C (ethylene), and D (propane). These materials are grouped according to the ignition temperature of the substance, its explosion pressure, and other flammable characteristics.

• Class II Groups - Groups E (metal dusts), F (carbon dusts), and G (grain dusts). These materials are grouped according to the ignition temperature and the conductivity of the hazardous substance.

• Class III Groups - These materials include wood-working and textiles that are easily ignitable, but not likely to be explosive.